Hydraulic accumulator in form of a bellows accumulator

ABSTRACT

The invention relates to a hydraulic accumulator, comprising an accumulator housing ( 1 ), in which a bellows ( 21 ) having a selectable number of pleats ( 23 ) forms a mobile separation element between the gas side ( 25 ) and the fluid side ( 13 ), characterized in that a distancing device ( 33 ) is provided arranged inside the accumulator housing ( 1 ), and is fluidically connected to the inside of the bellows ( 21 ) or abuts to the bellows ( 21 ), thus forming an additional medium chamber.

The invention relates to a hydraulic accumulator in the form of a bellows accumulator, having an accumulator housing, in which the bellows, having a preselectable number of pleats, forms a movable separation element between the gas side and the fluid side.

Hydraulic accumulators having bellows serving as a movable separation element are known and are used in various technical fields, for example, in hydraulic brake systems for motor vehicles and in a wide variety of industrial hydraulic systems. For example, DE 10 2008 061 221 A1 discloses a bellows accumulator, in which a metal bellows is provided as the movable separation element between the gas side and the fluid side.

Bellows accumulators are characterized by many advantageous properties. For example, relatively great changes in volume of the media spaces in the accumulator housing can be implemented by expanding and contracting the bellows. Metal bellows provided as the movable separation element are also relatively robust with respect to alternating loads, such as those which may occur during operation, in particular in use as a pulsating damper, and they have good sealing properties without any diffusion losses. However, these properties must be balanced against the fact that metal bellows, which may be considered for use in hydraulic accumulators,

are relatively expensive components, so that manufacturing the bellows accumulators is relatively cost intensive.

In this regard, the object of the invention is to make available a bellows accumulator which can be manufactured inexpensively and economically.

According to the invention, this object is achieved by a bellows accumulator having the features of patent claim 1 in its entirety.

Thus, an important special feature of the invention is that a spacer device is provided, disposed inside the accumulator housing, and in fluid connection with the interior of the bellows, forming an additional media space, or being adjacent to the bellows. A desired total volume of the working spaces in the accumulator housing can be implemented through pleated bellows having smaller dimensions and a smaller number of pleats accordingly, due to the fact that, by means of the spacer device in addition to the volume of the working space, which forms the interior of the bellows in its working movements or lifting movements and depends on the geometry and the number of the bellows behaviors, this yields a significant reduction in manufacturing costs. Another advantage is that, due to the different choice of the size of the additional volume made available by the spacer device, different total volumes can be implemented with bellows of the same number of pleats. Due to the possibility of using similar bellows for hydraulic accumulators of different specifications, this opens the possibility of a further cost reduction due to the use of bellows, which conform to a standard size and can thus be manufactured economically and inexpensively in larger numbers.

In advantageous exemplary embodiments, the spacer device is in the form of a pot, which is mounted with a fluid-tight connection, with its opening on an open end of the bellows. A suitably selected depth of the pot can easily provide the desired additional volume in this way.

The arrangement may advantageously be made so that the pot is held immovably axially in the accumulator housing and forms the attachment point for the immovable end of the bellows at its opening.

Alternatively, however, the pot may be disposed as a movable element on the movable end of the bellows and its immovable end may be secured on the accumulator housing in this case.

In both cases, the interior of the bellows may be assigned to the gas side in a particularly advantageous manner, so that the volume of the additional media space formed by the pot, together with the interior of the bellows, forms the volume of the gas side, so that a large volume of working gas, accordingly, is available for operation of the hydraulic accumulator.

In preferred exemplary embodiments, with the pot disposed so that it is axially immovable, its bottom is at one end of the accumulator housing and has a gas filling connection for a working gas.

In exemplary embodiments, in which the pot is connected to the movable end of the bellows, the immovable end of the bellows may be secured on a housing part situated at one end of the accumulator housing, where a gas filling connection for working gas is provided.

In advantageous exemplary embodiments, a housing end part may be provided on the end of the accumulator housing opposite the end having the gas filling connection, such that this housing end part delimits the fluid side, which is on the outside of the bellows and has a fluid connection.

The housing end part may especially advantageously form a stop, which limits the movements of the bellows to a stroke corresponding to a predefined maximum volume comprised of the volume of the interior of the bellows and the additional volume of the pot.

The invention is explained in greater detail below on the basis of the exemplary embodiments depicted in the drawings, which show:

FIG. 1 an exemplary embodiment of the hydraulic accumulator according to the invention, one half side shown in a side view and the other half in a longitudinal section;

FIG. 2 a diagram of a second exemplary embodiment corresponding to FIG. 1;

FIG. 3 a modified implementation of this exemplary embodiment in an illustration corresponding to FIG. 1, and

FIG. 4 a modified implementation of this embodiment in an illustration corresponding to FIG. 2.

The exemplary embodiments illustrated in FIGS. 1 and 2 have an accumulator housing 1, which has a semi-cylindrical interior and is closed on the end 3 (at the top of the drawing) except for a central opening 5. At the lower end 7, the accumulator housing 1 is closed by a housing end part 9, which has a centrally positioned fluid connection 11 leading to the fluid side 13 in the interior. The end part 9 is secured by a snap ring 15 and is sealed with respect to the accumulator housing 1 by means of a sealing element 17. The housing end part 9 is in the form of a flat plate with an elastomeric ring element 19 disposed in an annular groove in the plane facing the interior, this groove protruding slightly above the plane of the end part 9.

In the interior of the accumulator housing 1, there is a metal bellows 21 having a predefined number of bellows pleats 23, only some of which are labeled in the figures, as the separation element between the fluid side 13 and a gas side 25. The bellows 21 is open at the end 27 at the top in the drawing and is closed at its other lower end 29, such that in the exemplary embodiment in FIG. 1, an end part 31 in the form of a thin plate connected to the last bellows pleat 23 on the movable end 29 of the bellows 21 is provided. In the exemplary embodiment of FIG. 1, the bellows 21 is connected at its other open end 27 to a spacer device, which is in the form of a pot 33 that is secured in the accumulator housing 1 so that it is immovable axially. The pot 33 is connected to the last pleat 23 of the bellows 21 at the edge 35 of its opening, so that the interior of the pot 33 is in fluid connection with the interior of the bellows 21 and thus forms an extra volume in addition to the volume of the bellows 21. At the same time, the opening edge 35 of the pot 33 forms the locking point for the immovable end 27 of the bellows 21. The pot 33, which is sealed by a sealing element 37 on the outside with respect to the accumulator housing 1, has a gas filling connection 39 on the bottom of the pot, which is accessible through the opening 5 in the accumulator housing 1. In the operating state illustrated in FIG. 1, in which a prestressing pressure prevails on the gas side 25 and thus inside the pot 33 and in the interior of the bellows 21, and the fluid side 13 is pressureless, the housing end part 9 forms a stop to limit the stroke for the end part 31 on the movable end 29 of the bellows 21, so that the ring element 19 on the end part 9 forms a flexible contact point.

The example of FIG. 2 thus differs from the prior art inasmuch as the immovable open end 27, which is at the top in the figure, is no longer connected to the spacer device but instead is secured on a housing part 41, which is situated at the upper end 3 of the accumulator housing 1, as the pot 33 of the first exemplary embodiment is sealed by means of a sealing element 37. In a manner similar to that with the pot 33 of the first exemplary embodiment, a gas filling connection 39, which is accessible through the opening 5, is also situated in the housing part 41 in the central part. Unlike the example from FIG. 1, a pot 33 which serves as the spacer device is not mounted on the immovable end 27 but rather on the movable end 29 of the bellows, such that the pot 33, as a component that is movable with the bellows 21, is designed with thin walls and comes to rest against the flexible ring element 19 of the housing end part 9 with the pot bottom 43 at the maximum stroke of the bellows 21 to limit the stroke.

The exemplary embodiment of FIG. 3 differs from the example of FIG. 1 only inasmuch as the accumulator housing 1 is in the form of a tube, which is continuous on the inside from the lower end 7 to the upper end 3. Whereas in the first exemplary embodiment of FIG. 1, the pot 33 forming the additional volume of the bellows 21 is supported on the closed upper end 3 of the accumulator housing 1, in the example of FIG. 3, the pot 33 is secured by means of a snap ring 61 on the upper open tube end 3 of the accumulator housing 1.

The example of FIG. 4 corresponds to the exemplary embodiment of FIG. 2, except for the fact that the accumulator housing 1 is again designed as a tubular body. Accordingly, the housing part 41, which is connected to the immovable end 27, is secured axially on the open tube end 3 of the accumulator housing 1 by means of a snap ring 61.

Manufacturing the accumulator housing 1 from a tube body permits a particularly simple, economical and inexpensive production of the bellows accumulator.

As this shows, hydraulic accumulators of various specifications according to the invention can be designed with bellows 21 having the same number of bellows pleats 23, by preselecting a minimum volume through the choice of the depth of the respective pot 33, such that this volume corresponds essentially to the volume of the pot 33 with the bellows 21 compressed. On the other hand, the maximum volume of the other media space, which is on the outside of the compressed bellows 21, is predetermined through the choice of the axial length of the accumulator housing 1. 

1. A hydraulic accumulator in the form of a bellows accumulator, having an accumulator housing (1), in which the bellows (21), having a preselectable number of pleats (23), forms a movable separation element between the gas side (25) and the fluid side (13), characterized in that a spacer device (33) which is disposed inside the accumulator housing (1) and is in fluid connection with the interior of the bellows (21) is provided, forming an additional media space, or is adjacent to the bellows (21).
 2. The hydraulic accumulator according to claim 1, characterized in that the spacer device is in the form of a pot (33), which is mounted with its opening (35) on an open end of the bellows (21) with a fluid-tight connection.
 3. The hydraulic accumulator according to claim 1, characterized in that the pot (33) is held in an axially immovable position in the accumulator housing (1) and forms the securing point for the immovable end (27) of the bellows (21) at its opening (35).
 4. The hydraulic accumulator according to claim 1, characterized in that the pot (33) is disposed on the movable end (29) of the bellows (21), the immovable end (27) being secured on the accumulator housing (1).
 5. The hydraulic accumulator according to claim 1, characterized in that the bottom of the axially immovable pot (33) is situated at one end (3) of the accumulator housing (1) and has a gas filling connection (39) for a working gas.
 6. The hydraulic accumulator according to claim 1, characterized in that the immovable end (27) of the bellows (21) is secured on a housing part (4 1) situated at one end (3) of the accumulator housing (1), where a gas filling connection (39) for a working gas is provided.
 7. The hydraulic accumulator according to claim 1, characterized in that a housing end part (9) is provided on the end (7) of the accumulator housing (1), which is opposite the end (3) assigned to the gas filling connection (39), this housing end part having a fluid connection (11) and bordering the fluid side (13) on the outside of the bellows (21).
 8. The hydraulic accumulator according to claim 1, characterized in that the housing end part (9) forms a stop which limits the movements of the bellows (21) to a stroke corresponding to a predefined maximum volume comprised of the volume of the interior of the bellows (21) plus the additional volume of the pot (33). 